Fast Fabrication of High-Performance CoSb₃-Based Thermoelectric Skutterudites via One-Step Yb-Promoted Peritectic Solidification

As a most promising mid-temperature thermoelectric material, CoSb₃-based bulk material exhibits an applicable figure-of-merit (ZT) of more than one. However, their fabrication is historically time-consuming due to the long-time solid-state phase transitions from CoSb₂ to CoSb₃. To overcome this challenge, here, a fast one-step process is developed to fabricate n-type Yb-doped CoSb₃ with stable ZT of 1.12 at 765 K in <5 h. Experiments confirm Yb promotes peritectic reactions of CoSb + Liquid → CoSb₂ and CoSb₂ + Liquid → CoSb₃, optimizes power factor, and suppresses thermal conductivity. Moreover, the dense grains, induced by the one-step crystallization, result in outstanding mechanical properties with a Young's modulus of 171.4 GPa and a hardness of 8.8 GPa in the Yb-doped CoSb₃. This study indicates that the fast one-step fabrication route can effectively promote the practical applications of CoSb₃-based thermoelectrics and provide guidance for thermoelectric fabrication via rational phase design.